Many mobile phones support automatic location detection, using one of several positioning systems, or using multiple positioning systems in combination. Global positioning systems (GPS) detect position via satellite data. Triangulation positioning systems detect position by measuring signal strengths received at a mobile phone from three or more radio towers.
As many mobile phone owners constantly carry their mobile phones with them, automatic location detection has become of particular advantage for emergency use. Location of a mobile phone during an emergency may be critical for saving the mobile phone owner's life. An enhanced 9-1-1 service (E9-1-1) is available in North America for locating mobile phones during emergencies. When a caller makes an emergency call to E9-1-1, E9-1-1 associates a physical address with the caller's phone number, and routes the call to the most appropriate Public Safety Answering Point for the physical address.
Automatic location detection is also of advantage for non-emergency use, both for the mobile phone owner, and for others who would like to know the owner's whereabouts.
In some situations, a user would like to know his whereabouts relative to other users and locations, or the whereabouts of a designated person relative to other people and locations. Prior art location detection applications do not readily provide such information in a user-friendly way.